1. Field of the Invention
This invention is directed to assemblies and methods for monitoring in situ, controlling and adjusting the thickness distribution of an electroplated material on an object in an electroplating process. The object can be of any shape as long as it can be electrically charged.
2. Description of Related Art
U.S. Pat. No. 4,659,446 discloses cup-like shields of a non-conductive acid-resistant material that are secured at opposite ends of a cylinder for rotation with the cylinder and extend radially outwardly. The shields have a configuration such as to control the thickness of the metal deposited on the cylinder. However, the method has the disadvantage that cylinders of different diameters or lengths would need dedicated cup-like shields of different dimensions. Besides, the method can not monitor in-situ the distribution of the electroplated material.
U.S. Pat. No. 5,318,683 provides an electrodeposition apparatus and a method for reconditioning a gravure cylinder through electrodeposition. The apparatus includes a barrier member and a diffusion member that can prevent contaminants, e.g. soils and oxides, from moving into contact with the object being electroplated and also facilitate the dispersion of ions in the electroplating bath. The method disclosed, however, is not effective for controlling and adjusting the thickness distribution on the object because both the distribution of electrical field and deposition time along the cylinder's longitudinal axis are not controlled.
U.S. Pat. No. 6,929,723 discloses an apparatus for electroplating a rotogravure cylinder. The apparatus includes a non-dissolvable anode and an ultrasonic system that introduces wave energy into the plating solution. While the reference addresses several problems and quality issues in the electroplating of the rotogravure cylinder, the thickness distribution of the plated material cannot be controlled for the same reason as described for the method of U.S. Pat. No. 5,318,683.
Therefore there is still a need for methods to monitor, control and adjust the thickness distribution of an electroplated material in an electroplating process. A method which can monitor in situ the thickness distribution is particularly desirable.